Update project_setup.md (#1558)

Author: redvimo

book/src/project_setup.md

@@ -4,9 +4,10 @@ Let's begin by installing all necessary tools.
 First, follow the instructions on the [GTK website](https://www.gtk.org/docs/installations/) in order to install GTK 4.
 Then install Rust with [rustup](https://rustup.rs/).
 
-Now, create a new project by executing:
+Now, create a new project and move into the newly created folder by executing:
 ```
 cargo new my-gtk-app
+cd my-gtk-app
 ```
 
 Find out the GTK 4 version on your machine by running